Dear All,
Herewith I am attaching crystal structure files of FAPbI3 with Imm2 space group (in Imm2, ' I ' stands for body centered) and MAPbI3 with Pm-3m space group. so I have two doubts that how can I consider FAPbI3 as body center structure and in MAPbI3 crystal structure, MA molecule (CH3NH3) as a single atom during fulfilling space group? Or I have considered wrong structures.
Please also try to share a proper related article.
Thank you
The formamidinium and dimethyl ammonium molecules are treated as a single entity, not an atom. Both of them are called Perovskite types and not Perovskites. While calculating the tolerance factor these molecules are treated as a cylinder and the cylinder radius and height are used for calculation. I have attached an article with this which will help you to understand the tolerance factors of Metal Organic Frameworks. You have used the triclinic space group for drawing the structure of both the MAPbI3 and FAPbI3. Actually, MAPbI3 is an orthorhombic structure material. Similarly, FAPbI3 belongs to some other structure, and I will send you the detail tomorrow.
The attached paper will give you a feel of MOFs and their tolerance factors. In fact, I am answering your question without referring to any data in my hand tomorrow after going to the office I will check the structural database and give you the actual picture. Whatever you have drawn with space group no. 1 (P1) is not correct.
Dear Dharmadoss Sornadurai sir, could you please help me to know that How can I say FAPbI3 as a body centered ?
I am attaching one article, please check it
Actually particularly I wish to verify space group Imm2 for FAPbI3. As I asked for MAPbI3 crystal structure, so I got the idea that any molecule in the body centered could be considered as single atom because it is not sharing its fractional with any one. and for that I wish any reference to cite this statement. So MAPbI3 is verified Pm-3m space group.
Again please don't consider MA as an atom, because it is a molecule, consider it as a single entity for the purpose of tolerance factor calculation.
Dharmadoss Sornadurai I apologized. Thank You
Could you please have few words for FAPbI3 ?
I have lot of collections of MOFs and a part of is based on FA based perovskite. Actually there is one article which speaks about the structural details. At 300 K it is cubic (Pm-3m SG) and at 151 K and 91 K it is in tetragonal structure with P4/mbm SG. Unfortunately there is no atomic positions available for it. I will search and try to get it. Now I have attached all the three data for your reference.
Dear Dharmadoss Sornadurai Sir,
First of all, I want to appreciate your efforts toward my query. Actually I am looking for body centered (Imm2 Space group) as attached above paper.
Unfortunately, with this structure, there is no data available for FAPbI3, I am searching for it. If you get it send it to me otherwise if I am getting I will send to you.
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